Advanced structural damping systems such as magnetorheological (MR) dampers have great potential improve our ability to achieve performance-based structural design (PBD) directed towards seismic resilience. However, developing methods for real-time hybrid (RTH) testing of these systems is essential to enable the validation of these approaches. In this NEESR project, large-scale structural models, controlled with MR devices are being tested at the Lehigh RTMD NEES Equipment Site using RTH techniques. [less]

The vision for this research is a validated probabilistic, performance-based seismic design procedure for buildings with passive damping systems. In this procedure, the design of the damping system is integrated with the design of the associated seis...
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The vision for this research is a validated probabilistic, performance-based seismic design procedure for buildings with passive damping systems. In this procedure, the design of the damping system is integrated with the design of the associated seismic load resisting frames. The uncertainties that influence the level of damage caused by ground motions at different seismic input levels are treated explicitly using probabilistic methods. The procedure considers multiple performance objectives, with each objective associating a different level of damage with a different seismic hazard level. The project will design two steel-framed prototype buildings as the context for the research. Several types of dampers will be studied. Tests at the Lehigh NEES equipment site will characterize the dampers; analytical models for the dampers will be calibrated and validated. Extending previous work, a practical performance-based design procedure, and an associated design assessment procedure for buildings with passive dampers will be developed. These procedures treat inherent uncertainties using partial safety factors. The performance-based design procedure will be used to produce several design cases for each prototype building. The strength of the steel frames and the damper type will be varied among the design cases. Then, each design case will be assessed with a rigorous, probabilistic assessment procedure developed by the project. This assessment uses nonlinear dynamic analyses, and considers the possible damage states of the building while rigorously treating uncertainties in building properties, damping systems, and ground motions. The procedure estimates the probabilities that these damage states are reached at different seismic hazard (input) levels. Large-scale, real-time hybrid simulations at the Lehigh NEES equipment site will validate the rigorous assessment procedure as well as the results of the practical performance-based design procedure. The hybrid simulations will have two phases: Phase 1 uses three individual large-scale dampers as the lab specimens, while the remainder of the building is modeled as an analytical substructure; Phase 2 uses a large-scale, three-story steel frame with dampers as the lab specimen, while the remainder of the building is modeled as an analytical substructure. Phase 1 simulations will be particularly efficient, by enabling numerous ground motions to be applied to the building, resulting in various levels of damage, without the need to repair the test specimens, since the damage will be within the analytical substructures. Phase 2 simulations will validate the overall project approach. This research will produce a validated, rigorous, probabilistic seismic performance assessment procedure for buildings with passive damping systems which addresses significant uncertainties in building performance. This research will also produce a validated, practical, multi-level, probabilistic, performance-based seismic design procedure for buildings with passive damping systems. Full-scale damper characterization test data sets will be produced. Validated analytical models for passive dampers, suitable for numerical simulations, will also be produced. Reliable and well-documented data sets from large-scale, real-time hybrid seismic simulations of buildings with passive dampers will be produced and used to validate the design and assessment procedures.
This research will produce the knowledge needed to move the performance-based seismic design procedure into practice. [less]

The project is investigating a family of innovative self-centering (SC) steel frame systems with the potential to withstand the currently accepted design basis earthquake (DBE) for buildings without damage. The project goals are: to develop fundament...
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The project is investigating a family of innovative self-centering (SC) steel frame systems with the potential to withstand the currently accepted design basis earthquake (DBE) for buildings without damage. The project goals are: to develop fundamental knowledge of the seismic behavior of SC steel frame systems; to conduct integrated design, analysis, and experimental research on SC steel frame systems, using the enabling facilities of NEES; to develop performance-based, reliability-based seismic design procedures and criteria for SC steel frame systems; and to educate students and practitioners with fundamental and practical knowledge about SC steel frame systems. The project team is multi-organizational, involving Lehigh, Princeton, and Purdue Universities, multi-disciplinary and diverse. The team includes international participation from the National Center for Research on Earthquake Engineering (NCREE) in Taiwan, and will be advised by a board of individuals from engineering firms well known in the US and international earthquake and structural engineering communities. This material is based upon work supported by the National Science Foundation under Grant No. 0420974. [less]

Devel. Of Advanced Servo-Hydraulic Control And Testbed For Real-time

Status: Completed
Planned for 2009-06-15 10:00 EST

Recently there have been a number of new devices developed that enables structural systems to withstand earthquake loading with minimal damage. Examples of these devices include passive dampers and semi-active dampers. In order to evaluate the seismi...
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Recently there have been a number of new devices developed that enables structural systems to withstand earthquake loading with minimal damage. Examples of these devices include passive dampers and semi-active dampers. In order to evaluate the seismic performance of structural systems outfitted with these devices, it is imperative the load-rate effects be considered in any laboratory simulation. The current study will develop advanced state space control to be implemented into the RTMD facility. The project will involve constructing a damper test bed, consisting of the damper attached to the laboratory floor and dynamically loaded in real-time using NEES servo-hydraulic actuators. A reaction bracket will be utilized to attach the damper to the laboratory floor. State space control laws will be developed using actuator displacement, velocity, differential chamber pressure, and actuator load cell feedback states. PID control laws will be improved using feed forward of the derivative of the command signal. Due to the ability to empirically test the damper, real-time testing methodologies and damper effectiveness with regard to earthquake hazard mitigation will be evaluated. Performance data will also be collected to aid in the establishment of a performance-based design methodology. This material is based upon work supported by the Pennsylvania Infrastructure Technology Alliance under award number PIT-656-06. [less]

Development of a Seismic Design Methodology for Precast Floor Diaphrag

Status: Completed
Planned for 2007-11-08 10:30 EST

A consortium comprised of the University of Arizona (UA), the University of California San Diego (UCSD), and Lehigh University (LU), together with the Precast/Prestressed Concrete Institute (PCI), is conducting a collaborative research project to dev...
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A consortium comprised of the University of Arizona (UA), the University of California San Diego (UCSD), and Lehigh University (LU), together with the Precast/Prestressed Concrete Institute (PCI), is conducting a collaborative research project to develop a comprehensive, accurate, and efficient design methodology for precast concrete floor diaphragms in buildings under seismic loading. Using closely integrated experimental and analytical simulations, the project will significantly advance knowledge of the seismic behavior of precast floor diaphragms and develop information on the stiffness, strength, and ductility capacity of critical precast diaphragm elements. Integrating these results with industry knowledge, the project will produce an appropriate seismic design methodology. The development of an appropriate seismic design methodology for precast concrete floor diaphragms is challenging and will integrate the following to further investigate: (1) large-scale experiments to determine the flexibility, strength, and ductility of critical diaphragm elements by applying both simple cyclic force patterns and histories, and complex (multi-degree-of-freedom) force patterns and histories; (2) detailed finite element (FE) analyses of complete floor diaphragms (under seismic load) to determine critical force patterns and histories for diaphragm elements that will be applied in the experiments and used in developing diaphragm design requirements; (3) nonlinear time-history dynamic analyses (NTDA) of prototype buildings to determine diaphragm seismic force levels; (4) quasi-static diaphragm tests and shaking table tests of entire structures to verify the FE and NTDA results and provide added input into the large-scale experiments on critical diaphragm elements; and (5) industry knowledge of precast construction methods and economics, design practices, and design code development issues. This material is based upon work supported by the National Science Foundation under award number CMS-0324522. [less]

Multi-Site Soil-Structure-Foundation Interaction Test (MISST)

Status: Completed
Planned for 2006-05-16 07:00 EST

MISST is intended to provide a realistic test bed application with which to verify and extend all components of the NEESgrid as well as all components of the sites taking part in the distributed simulation. Concurrently, it is intended to extend the...
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MISST is intended to provide a realistic test bed application with which to verify and extend all components of the NEESgrid as well as all components of the sites taking part in the distributed simulation. Concurrently, it is intended to extend the state-of-the-art in integrated experimental-analytical simulation earthquake engineering. MISST utilizes four aspects of simulation that will comprise many of the applications of the NEES experimental sites (ES) and NEESgrid by including: Advanced analytical geotechnical modeling under dynamic loading, advanced analytical structural modeling under dynamic loading, advanced geotechnical testing using centrifuges, and advanced structural testing using multi-degrees-of-freedom testing facilities. The following equipment sites, along with the National Center for Supercomputing Applications, are involved in the project: Lehigh University, University of Illinois, Urbana-Champaign, and Rensselaer Polytechnic Institute.This material is based upon work supported by the National Science Foundation under Grant No.0407555 [less]

Investigation of Prototype Elastomeric Damper Characteristics

Status: Completed
Planned for 2006-04-14 10:45 EST

The main purpose of this study is to determine the material properties and performance of prototype elastomeric dampers developed by Penn State Erie and Corry Rubber Company, with the goal of helping to create recommendations for improvement upon the...
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The main purpose of this study is to determine the material properties and performance of prototype elastomeric dampers developed by Penn State Erie and Corry Rubber Company, with the goal of helping to create recommendations for improvement upon the damper design. The assigned loading protocol uses the hysteretic behavior of the damping material under loading to determine a series of properties, including the stiffness and loss factors of the material. These tests will also determine the materiala??s susceptibility to ambient temperature and internal temperature changes. The test setup uses NEES dynamic actuators to load the dampers at different displacement amplitude and frequency combinations and assesses the effects of these factors on the dampers. [less]